Power BI Content pack office365 - Behind the scenes?

maybe a stupid question, but i'm curious if there is documentation available which explains in general what API / Powershell code is used to get values for each of the properties within the Content Pack.

just to pick one example:

Whenever you switch to EDIT mode, you see a lot of keys on the right side (fields).

e.g.   UserActivity\EXO_AvgEmailRead   --> what code is behind of that particular key ? 

if a simple table exists where one can see how this data is retrieved it would be pretty cool and helpful.

I hope it is not just a blackbox :)

thanks